Fracture prediction in 4-point bending of an extruded aluminum panel

Currently, the ICE cab cars in Europe are of all-aluminum construction for durability and low weight. Several serious train collisions involving this type of train raised questions about their integrity under accidental loads. A typical aluminum cab car is assembled from extruded aluminum panels, which are MIG welded, forming long seam lines. In this work, crushing characteristics of full scale sandwich panels under a 4-point bending load configuration were studied experimentally and numerically. Tests were run all the way to first fracture which occurred inside buckling induced dimples on the compressive side. The force-deflection response and fracture initiation were predicted by the finite element method and compared with experimental results. The location of the first fracture and the corresponding load was predicted with great accuracy using a newly developed fracture criterion. Based on a simplified beam model, a closed form analytical solution of the force-deflection response for the pre-fracture stage was also developed.